The present invention relates to a cooling system for cooling of a combustion engine.
Cooling systems for cooling of combustion engines in vehicles usually comprise a thermostat which regulates the temperature of the coolant in the cooling system. The thermostat comprises a sensing element and a valve. The sensing element may contain a wax substance which changes phase at the thermostat's regulating temperature. The sensing element causes the valve to direct the coolant to the engine without cooling at times when the coolant is at a lower temperature than the thermostat's regulating temperature. At times when the coolant is at a higher temperature than the thermostat's regulating temperature, the sensing element causes the valve to direct the coolant to a radiator for cooling. Such thermostats are inexpensive and operationally reliable.
Thermostats maintain a substantially constant operating temperature of the coolant in the cooling system. It is however not always desirable to maintain a constant operating temperature of the coolant in a cooling system. A known way of varying the operating temperature of the coolant is to provide the sensing element with an electrical warming element. Such a warming element may be used to cause the wax substance in the sensing element to be warmed and change phase at times when the coolant is at a lower temperature than the thermostat's regulating temperature. The coolant's operating temperature in the cooling system may be varied by varying the degree of warming of the wax substance.
SE 532 354 refers to a thermostat in a cooling system for cooling of a combustion engine. The thermostat comprises a valve situated in a line which receives warm coolant from the engine, and a sensing element situated in a pilot line in the cooling system where it monitors the temperature of the coolant which is led to the engine. In this case the temperature of the coolant which is led into the engine serves as the operating temperature. This temperature is in many cases a more relevant control parameter than the temperature of the warm coolant leaving the engine.